The present invention relates to a portable terminal apparatus and, more particularly, to the arrangement of keys of a portable terminal apparatus, a recording medium which stores a program for expanding the function of the portable terminal apparatus by the keys, and a method of controlling the portable terminal apparatus.
Recent portable terminal apparatuses represented by cellular phone sets and PDAs have been made more compact with multiple functions. Functions prepared in such a portable terminal apparatus are used, set, and selected by operating an input device such as keys provided on the apparatus main body. Along with the size reduction of the portable terminal apparatus main body, the input device must also be compact. A compact portable terminal apparatus having many functions is required to exhibit its functionality without sacrificing the user interface such as key input due to size reduction.
FIGS. 10A and 10B show the outer appearance of a conventional cellular phone set. A folding cellular phone set 1 comprises an upper case 2 and lower case 3. A display section 11 which displays various kinds of information is formed on the front side of the upper case 2. Operation keys 4 used to input operation are formed on the front side of the lower case 3. For the upper case 2 and lower case 3, surfaces that are exposed to the outside when the cellular phone set 1 is folded are defined as rear surfaces, and surfaces that are closed inside are defined as front surfaces.
Such a cellular phone set 1 achieves sufficient size reduction and therefore normally allows a user to support it by one hand and operate the operation keys 4 only by one finger and, more particularly, the thumb of the hand.
In the conventional cellular phone set, however, if the user wants to input a desired character or change one key function, he/she must perform complex operation to press the same key a plurality of number of times or operate another key to display a menu because the number of keys is limited by size reduction of the input device. In addition, it is very inefficient to perform such operation only by one finger, and long-time operation involves user's fatigue.